Good point. This should be more optimized. New variable 'neither' is a boolean set to true initially and set to false if n is either divisible by 3, 5, or both. Then that becomes the check for if neither is the case.
```
function output = fizzbuzz(n)
% fizzbuzz(n) returns 'Fizz' if n is a multiple of 3, 
% 'Buzz' if n is a multiple of 5, 'FizzBuzz' if n is a 
% multiple of 5 and 3, and returns n if it is neither a 
% multiple of 3 or 5.
% Format of Call: fizzbuzz(n);
% Returns: output = 'Fizz', 'Buzz', 'FizzBuzz', or n 
% based on if n is a multiple of 3 or 5
    
    if ~isnumeric(n)
        error('Error: Input must be a number, not a %s.',class(n));
    else
        neither = true;
        output = '';
        if rem(n,3) == 0
            output = 'Fizz';
            neither = false;
        end
        if rem(n,5) == 0
            output = strcat(output,'Buzz');
            neither = false;
        end
        if neither
            output = num2str(n);
        end
    end
```